4045-50-5Relevant academic research and scientific papers
Metal nanocrystals embedded in single nanocrystals of MOFs give unusual selectivity as heterogeneous catalysts
Na, Kyungsu,Choi, Kyung Min,Yaghi, Omar M.,Somorjai, Gabor A.
, p. 5979 - 5983 (2014)
The growth of nanocrystalline metal-organic frameworks (nMOFs) around metal nanocrystals (NCs) is useful in controlling the chemistry and metric of metal NCs. In this Letter, we show rare examples of nMOFs grown in monocrystalline form around metal NCs. Specifically, Pt NCs were subjected to reactions yielding Zr(IV) nMOFs [Zr6O4(OH)4(fumarate)6, MOF-801; Zr6O4(OH)4(BDC)6 (BDC = 1,4-benzenedicarboxylate), UiO-66; Zr6O4(OH)4(BPDC)6 (BPDC = 4,4′-biphenyldicarboxylate), UiO-67] as a single crystal within which the Pt NCs are embedded. These constructs (Pt?nMOF)nanocrystal are found to be active in gas-phase hydrogenative conversion of methylcyclopentane (MCP) and give unusual product selectivity. The Pt?nUiO-66 shows selectivity to C6-cyclic hydrocarbons such as cyclohexane and benzene that takes place with 100 °C lower temperature than the standard reaction (Pt-on-SiO2). We observe a pore size effect in the nMOF series where the small pore of Pt?nMOF-801 does not produce the same products, while the larger pore Pt?nUiO-67 catalyst provides the same products but with different selectivity. The (Pt?nMOF)nanocrystal spent catalyst is found to maintain the original crystallinity, and be recyclable without any byproduct residues.
An Electron Spin Resonance Study of the Methylcyclopentadienyl Radicals, MenH5-nC5 (n=1-5)
Davies, Alwyn G.,Lusztyk, Ewa,Lusztyk, Janusz
, p. 729 - 736 (2007/10/02)
The radicals MenC5H5-n have been generated by photolysis of the corresponding hydrocarbons (n=3-5) or mercury derivatives (n=0-5) and their e.s.r. spectra have been recorded.The spectra are interpreted in terms of thermal population of the ψA and ψS molecular orbitals, for which the predicted hyperfine coupling constants are calculated by the McLachlan equation, taking λ 0.75 and Q(C5H5) -30 and Q(Me5C5) 31.85 G.The energy separations between the ψA and ψS MOs can be rationalised on the assumption that a methyl substituent on a carbon atom of the cyclopentadienyl carrying a unit ?-electron has a destablising interaction, within a factor of two, of 10 kJ mol-1.
